gas turbine - partload and operational...

6B Users Conference | San Antonio, TX | June 19-22, 2017

Gas Turbine - Partload and Operational TradeoffsMichael A. Cocca

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1


4 Effectors for turbine operation + one

2

Air flow

Exhaust Energy

Pressure ratio

T-Fire/Fuel flow

Turbine/cycle efficiency


What are my effectors?

Legend:

IGV

TTXM

– critical effectors

– critical sensors(F)

(Units)

IGV

S

P

IBH

TTXMCTD

CPD

CTIM

TNH

SRV

FPG2

DWATT

~Other Critical Control Parameters:TFIRE- Firing temperatureCRT – Combustion reference temperatureTNHCOR – inlet temp-corrected speedCPR – compressor pressure ratio

AFPCS

AFPAP

ATID

(MW)

(inHg)

(F)

(psig)

(F)

(%)

(F)

(inH2O)

(psig)

(F)

C

Comb

T

What is FSR?FSR stands for Fuel Stroke Reference. FSR is the key fuel control output, configured to be proportional to the fuel heat consumption (BTU/sec). FSR can be thought of as though there it were the position of a single “virtual” gas control valve for the turbine.

What are fuel splits?A “split” is the proportion of fuel that is delivered to a particular combustion gas passage. In any given DLN system configuration with N valves, there are N-1 split effectors (since the sum of the fuel is

prescribed by FSR, you lose one degree of freedom in splits).

Gas Turbine Effectors / Sensors

What is IGV?What is IBH?

IGV stands for Inlet Guide Vanes. IGV (csrgv signal name) refers to

the vanes at the compressor inlet that affect air flow. Opening the IGV increases air flow through the compressor and hence the gas turbine.

IBH stands for Inlet Bleed Heat. IBH refers to recycling compressor outlet flow back to the compressor inlet. IBH acts to increase air flow through the compressor while decreasing air flow

through the gas turbine. The primary use is Compressor surge and icing protection.


Every plant decision comes with tradeoffs

Raise Efficiency

Increase Output

Increase Availability

Reduce Maintenance Costs

Enhance Flexibility

Balance Wear & Tear

ImproveReliability

Stretching or how to get more Flexible


6

Axial Fuel Staging (“Turndown Enhance”)Greater operating flexibility with improved emissions

CTQ Performance*

Fuel Flex 32% H2 content

Emissions 0.7 ppm NOx or 85% CO reduction

Turndown Down to 30% of Baseload

Potential additional benefits:

➢ Up to 2% fuel burn reduction at part load

➢ ~0.4% simple cycle efficiency improvement

➢ Peak fire up to +100F while remaining NOx compliant (alternative to turndown capability)

➢ Wider ambient temperature emissions compliance

✓ Extends the combustion system by 8”✓ Applicable to both DLN1 and DLN1+✓ Available to quote

* Estimated values based on NG operation at ISO conditions. Illustrative purposes only.


Axial Fuel Staging (“Turndown Enhance”)Hardware AFS CM&U Difference between DLN1+ LN and ULN

Secondary Fuel Nozzle May use existing partsTransfer Style Transferless Style

IdenticalDLN1+ LN-FlangedDLN1+ULN-Flangless

Endcover Assembly May use existing parts IdenticalCombustion Casing May modify existing casing Identical

Liner Modify or buy new2 rows of mixing holes on DLN1 vs. 3 on ULN, and thicker liner stops on ULN

Flow Sleeve Modify or buy new IdenticalAFS Injectors New part IdenticalAFS Thimbles New part IdenticalTransition Piece Use existing design Different dilution holesCross-Fire Tubes New part Identical


Features and benefits

Operational flexibility, increased output and efficiency – retrofittable

DLN turndown enhance

• Reduced NOx (~25%) – concurrent NOx and CO emissions reductions also achievable with compliant operations

• Extended CO compliant turndown2 – from 60% to 35% of peak load1

• Emission compliant peak fire2 – additional output – Up to +100°F Tfireincrease with same current NOx levels1

• Improved ambient operating range 1

• Combustor pressure drop reduction – up to .4% improvement in SC efficiency1

• Part-load simple cycle efficiency – up to 2% fuel burn reduction (higher air and pressure ratio) 1

• Commonality/flexibility/tunability – reduced need for dilution retunes1

Wrapper Penetration Assembly

TP Modification to add four new chamfered dilution holes

DLN Turndown Enhance headset

DLN Turndown Enhance injector

TP Modified with DLN Turndown Enhance headset

1Compared to current 9E DLN combustion system without DLN Turndown Enhance2Emision compliant peak fire cannot be combined with Extended compliant turndown 8

Using power of Digital for Flexibility


Upgraded fundamental control technology

Corrected Parameter Control • Four separate calculations for primary

boundaries: Performance, Tfire, CO, NOx

• Corrections for ambient temperature, humidity, inlet/exhaust pressure drop

• Additional sensors; humidity & ambient TCs

CPC

Baseline DLN1 control• Single temperature control curve - multiple

operational boundaries implicit

• No corrections CPR

Iso-Therm

Tx_requestControl Curve

Tx

CPR

-

MIN

IMU

M

Tx

CPR

Iso-Therm

MIN

IMU

M

Tfire

Boundary

CPR

SH

DPin

DPex

CTD

Performance

CPR

SH

DPin

DPex

CTD

CO

Boundary

CPR

SH

DPin

DPex

CTD

CPC

NOx

Boundary

CPR

SH

DPin

DPex

CTD

MA

XIM

UM

Iso-Therm

Tfire

Boundary

CPR

SH

DPin

DPex

CTD

Performance

SH

DPin

DPex

CTD

CO

Boundary

SH

DPin

DPex

CTDNOx

Boundary

CPR

SH

DPin

DPex

CTD

MA

XIM

UM

CPR – Compressor Pressure RatioCTD – Compressor Discharge TemperatureCMHUM – Specific HumidityDPin/ex – Inlet and Exhaust Pressure Drop CDM input (optional)


Enhance DLN Performance

*Trademark of General Electric Company.

AUTOTUNE LT & DX• Correct parameter control – tighter

control (Tfire, NOx, CO, dynamics)

• Automated fuel split adjustments

• CEMS feedback optional (DX)

AUTO RECOVER from primary re-ignition• Automatic vs. manual discovery

• Load reduction of ~5% vs. ~50%

• Automatic return to premix ~15 seconds vs. 10-30 minutes

11


TRIP AVOIDANCE• Improved logic to avoid trips

• Intelligent signal selection and use

• System level data validation

• Alternative protective actions

Examples− Exhaust spread and over-temperature logic

− Secondary flame detector sensing logic

− Transfer purge protection

− Valve position faults

− Null bias compensation for gas control valve

− Enhanced vibration sensing and logic

12

Reduce unnecessary tripsOpFlex* Trip Avoidance

*Trademark of General Electric Company.


Identify faults before startupOpFlex* Start Assurance

STARTING RELIABILITY• Start permissive rationalization

• Pre-start system checks

• Start sequence display showing start process status

• Check system at any time upon command

START PERMISSIVE SWEEPS PROVIDING HIGHER RELIABILITY

13*Trademark of General Electric Company


Predix*: Connecting Data and People Throughout the Organization

Accessibility | Scalability | Ecosystem | Custom Apps

Maintenance Manger Plant Manager Asset Manager Trader CEO

*Trademark of General Electric Company


Power plant equipmentEdge supervisory control

Efficiency optimizer: How it works

15

OptimizerSolver engine

Power plant Heat rate

Digital twinPlant thermal models

Current

HR

Target

HR

Unit controlsCycle levers

User interfaceCommands and benefits

Edge UIConfigured to take user

inputs on current ambient and target plant output conditions; ability to run in manual or auto-

optimize mode

Digital twinPhysics models and

tracking filters to match

the physical plant;

feeds the optimizer

with plant cycle

parameters to solve for

best HR setpoints

Cycle levers GT turbine

temperature

GT inlet guide vanes

GT inlet bleed heat

GT load balancing

ST turbine

temperature

ST pressure

OptimizerPeriodically solves for minimum plant heat rate (HR) by generating optimized supervisory setpoints

(“cycle levers”) for the key production assets in the power plant. The result is reduced fuel consumption from

part load to baseload relative to the plant's baseline operating conditions

Plant Assets

Gas turbines

HRSG’s

Steam turbine

Condenser

Cooling tower

Setpoints


Digital delivers additional efficiency between intervals

16

+ 0.5 % with Digital

1 time HR improvementPost outage from Major

inspection and AGP

Hea

t ra

te

Time

Current HR

.5%

Heat rate decrease due to AGP

New AGP

Digital optimized

Upgrades provide benefits post outage

Digital adds ongoing value between intervals

Constantly tuning for best operating setpoints given ambient conditions, fuel composition at base load and part load

Questions?

gas turbine - partload and operational...

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